Landing gear door assembly

ABSTRACT

An aircraft landing gear door assembly includes a plurality of doors moveable between open positions, in which landing gear can be deployed through an aperture, and closed positions, in which the doors are closed across the aperture. The plurality of doors includes first and second doors arranged such that, when the landing gear is deployed, the second door is obstructed from moving between its open and closed positions while the first door is free to move between its open and closed positions. After the landing gear is deployed the first door is closed.

The present invention relates to an aircraft landing gear door assembly.

BACKGROUND OF THE INVENTION

A landing gear of an aircraft is typically moveable between a deployedposition, where the landing gear extends downwardly from the aircraftand wheels of the landing gear can engage a runway, and a storedposition where the landing gear is accommodated within appropriatelyshaped bays in the aircraft's fuselage or wing. So as not to interferewith the overall aerodynamic properties of the aircraft in flight, thebays are provided with doors which, when closed, conform to the shape ofthe aircraft body.

In a known landing gear door assembly, a pair of doors are provided. Inthe closed position of the doors the opening or aperture of the bayaccommodating the landing gear is closed across by the doors withadjacent edges of the doors extending along a generally longitudinalaxis spanning the aperture. Each door is hinged about a generallyhorizontal and longitudinal axis in the region of the edge of the dooropposite to the edge adjoining the other door, allowing the doors to berotated downwardly about the axes to open positions in which the doorsextend approximately vertically downwardly from the aircraft body. Itwill be understood that references to the horizontal and vertical andthe like, refer to a situation where the aircraft is at rest on ahorizontal runway.

The size of the pair of doors depends upon the size of the aperture thatthe doors must close over and the aperture must in turn be sufficientlylarge to allow passage of the landing gear during deployment. As aresult, if the landing gear is relatively large the doors must in turnbe relatively large. Such large doors are, however, disadvantageous froman aerodynamic and noise viewpoint when they are open and extendingdownwardly and outwardly from the aircraft body.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an aircraft landing geardoor assembly that overcomes or mitigates the problem referred to aboveand in particular enables an aircraft to employ a door assembly thatwhen open provides a relatively large aperture for deployment of landinggear without leading to a corresponding disadvantage from an aerodynamicand noise viewpoint.

According to the invention there is provided an aircraft landing geardoor assembly including a plurality of doors moveable between openpositions, in which landing gear can be deployed through an aperture,and closed positions, in which the doors are closed across the aperture,the plurality of doors including a first door and a second door, wherein

the first and second doors are so arranged that they are, in use,configurable in such a way that movement of one of the first and seconddoors for at least a part of the way between the open and closedpositions causes movement of the other of the first and second doors,and

the first and second doors are arranged such that, when the landing gearis deployed, the second door is obstructed from moving between its openand closed positions while the first door is free to move between itsopen and closed positions.

By providing two doors, the first of which is free to move between itsopen and closed positions when the landing gear is deployed, it becomespossible to close the first door after deployment of the landing gear.It is then only the second door which is likely to have any adverseaerodynamic effect and/or generate noise.

Preferably, the first and second doors are mounted such that they may bemoved together between the open and closed positions substantiallywithout any relative movement between the first and second doors.

The movement, for which one of the first and second doors is mounted,may be constrained. For example, the movement may be such that there isonly one degree of freedom when moving the door between the openposition and the closed position. The movement of said one of the firstand second doors may be constrained for substantially all of themovement between the open and closed positions. The movement of saidother of the first and second doors may also be constrained. Preferably,the first and second doors are both mounted for movement, which isconstrained.

One of the first and second doors is preferably mounted for rotationalmovement about a fixed axis. The first door is preferably mounted forrotational movement about an axis, which is preferably a fixed axis.Similarly the second door is preferably mounted for rotational movementabout an axis, which is preferably a fixed axis. Whilst it is possiblefor a door to be mounted such that its movement is a complex combinationof translational and rotational movements, fixed-axis rotation providesa simple and reliable design.

Preferably, the first and second doors are mounted for rotation about afixed axis, the fixed axes of rotation of the first and second doorsbeing substantially coincident.

It is possible to provide respective drives, for example, linearactuators, for each of the doors but it is also possible to provide adrive for the first door only and to move the second door by coupling itto the first door. Thus the first and second doors may be arranged to becoupled together to move as a single unit between their open and closedpositions, and be decoupled to enable the first door also to moveindependently of the second door between its open and closed positions.

The assembly preferably includes locking devices for locking some or allof the doors in their closed and/or open positions. In the case wherethe first and second doors are capable of being coupled together, it isespecially preferred to provide a locking device for locking the seconddoor in its open position.

Preferably, when the doors are in their open positions, the second dooris disposed below the first door. The second door is referred to as“below” the first door, if the major part of the second door is belowthe major part of the first door, even though there may be parts of thesecond door that are above parts of the first door. Preferably thesecond door is mounted on at least one arm which is connected at one endto the second door and is moveably mounted, preferably rotatablymounted, at its other end to allow the movement of the second doorbetween its open and closed positions. Preferably two or three such armsare provided for each door. When the second door is in its open positionand the landing gear is deployed, the second door is preferably disposedadjacent to the wheels of the landing gear.

Preferably, the first and second doors are each mounted for movement bymeans of a connection having a plurality of connection points, at leastone of the connection points of one of the first and second doors beingdisposed between two of the connection points of the other of the firstand second doors. In the case where the second door is mounted on twoarms, the point at which each arm is mounted for movement may beconsidered as comprising a connection point for example. In that case,the points at which the first door is mounted for movement may forexample include a connection that is disposed between the two points atwhich the two arms are movably mounted. Said connection may be in theform of a hinge mounted on a shaft or spindle. There may be an infinitenumber of notional connection points associated with each connection.The first and second doors are preferably mounted for rotation about thesame hinge.

In a conventional door assembly it is common for a pair of doors to beprovided. According to the invention the plurality of doors preferablyincludes a third door moveable between closed and open positions, thefirst and third doors defining a pair of doors on opposite sides of theaperture through which the landing gear is deployed. Like the firstdoor, the third door is preferably mounted for rotational movement aboutan axis, which is preferably a fixed axis, and is preferably arrangedsuch that, when the landing gear is deployed, it is free to move betweenits open and closed positions. When the doors are all closed, the seconddoor is preferably disposed between the first and third doors; in oneembodiment of the invention described below and employing three doors,the second door is disposed in the middle of the three doors and thearrangement is approximately symmetrical about a plane passing throughthe middle of the second door; in another embodiment of the inventiondescribed below a fourth door is provided, interacting with the thirddoor in substantially the same way as the second door interacts with thefirst door, and the arrangement is approximately symmetrical about aplane passing through an interface of the second and fourth doors. Thus,the plurality of doors may include a fourth door mounted for movementbetween closed and open positions, the third and fourth doors beingarranged such that, when the landing gear is deployed, the fourth dooris obstructed from moving between its open and closed positions whilethe third door is free to move between its open and closed positions. Itwill be understood that, because the first and third doors are a pair,the third door may include any or substantially all of the features ofthe first door. Similarly, the fourth door, being one of the pair ofdoors including the second door, may include any or substantially all ofthe features of the first door. Thus, the third and fourth doors mayincorporate any of the features described above in relation to the firstand second doors.

Preferably, in the closed position, at least one of the plurality ofdoors is surrounded by other doors of the plurality of doors for atleast 60% of its perimeter, preferably for at least 75% of its perimeterand more preferably for at least 90% of its perimeter. For example,where the doors include third and fourth doors as defined above, themajority of the perimeter, and preferably substantially the entireperimeter, of the second door is directly adjacent to one or more of thefirst, third and fourth doors. Similarly, the fourth door may be atleast partially, and preferably substantially completely, surrounded bythe first, second and third doors.

The first and second doors are preferably so shaped that, when closed, asignificant portion of the perimeter of the second door is separatedfrom the perimeter of the aperture by a significant portion of the firstdoor. For example, at least 60%, preferably at least 75% and morepreferably at least 90%, of the perimeter of the second door isseparated from the perimeter of the aperture. The first and seconddoors, when mounted for rotation about substantially the same axis, arepreferably so shaped that at least 60%, preferably at least 75% and morepreferably at least 90%, of the perimeter of the aperture that isaligned with (or more preferably separated by an angle of less than 30%from) the axis of rotation, is not directly adjacent to the second door.

Advantageously, one of the third and fourth doors is mounted so that thethird and fourth doors may be moved together for at least a part of theway between the open and closed positions substantially without anyrelative movement between the third and fourth doors.

Whilst, the landing gear door assembly of the present invention may beassociated with a nose landing gear of an aircraft, the landing geardoor assembly is preferably associated with a main landing gear. It willbe understood that in this context the term main landing gear is alanding gear that sustains a significant share of the loads sustained bythe landing gear of the aircraft during landing and would normally forthat reason exclude the nose landing gear.

The invention further provides an aircraft including a landing gear doorassembly according to the present invention and a landing gear withwhich the landing gear door assembly is associated.

The present invention also provides a method of operating a landing geardoor assembly including a plurality of doors moveable between openpositions, in which the doors provide an aperture through which landinggear can be deployed, and closed positions, in which the doors closeover the aperture, wherein the plurality of doors include first andsecond doors and the method includes the following steps:

opening the first and second doors, the opening of the doors comprisinga step in which the first and second doors are moved together,preferably substantially without any relative movement between the firstand second doors, deploying the landing gear; and

closing the first door while the landing gear is still deployed.

It will be understood that the method just described is typicallycarried out shortly prior to landing.

The method preferably further includes the following subsequent steps:

opening the first door;

retracting the landing gear; and

closing the first and second doors.

The closing of the doors advantageously comprises a step in which thefirst and second doors are moved together, preferably substantiallywithout any relative movement between the first and second doors.

It will be understood that those steps are typically carried out shortlyafter take off.

Similarly, the invention provides a method of operating a landing gearassembly including a plurality of doors moveable between open positions,in which the doors provide an aperture through which landing gear can bedeployed, and closed positions, in which the doors close over theaperture, wherein the plurality of doors include first and second doors,the method including the following steps:

providing the door assembly with the landing gear deployed, the firstdoor closed and the second door open;

opening the first door;

retracting the landing gear; and

closing the first and second doors, the closing of the doors comprisinga step in which the first and second doors are moved together,preferably substantially without any relative movement between the firstand second doors.

In that case the method preferably further includes the followingsubsequent steps:

-   -   opening the first and second doors;    -   deploying the landing gear; and    -   closing the first door while the landing gear is still deployed.

The opening of the doors advantageously comprises a step in which thefirst and second doors are moved together, preferably substantiallywithout any relative movement between the first and second doors.

It will be understood that the method just described involves the samesteps as that previously described but beginning with those steps thatare typically carried out shortly after take off.

Advantageously, the step of moving the first and second doors togetherin either of the above methods may be performed by effecting movement ofone of the doors and arranging for that movement to cause the other ofthe first and second doors to be moved.

The method is preferably carried out using a door assembly as describedabove. For example, the plurality of doors may include a third doormoveable between closed and open positions, the first and third doorsdefining a pair of doors on opposite sides of the aperture through whichthe landing gear is deployed, the third door being opened when the firstdoor is opened and closed when the first door is closed. Furthermore theplurality of doors may include a fourth door mounted for movementbetween closed and open positions, the fourth door being opened when thesecond door is opened and closed when the first door is closed. Themethod may include a step in which the third and fourth doors are movedtogether substantially without any movement between the third and fourthdoors.

According to a further aspect of the present invention there is providedan aircraft landing gear door assembly including a plurality of doorsmoveable between open positions, in which landing gear can be deployedthrough an aperture, and closed positions, in which the doors are closedacross the aperture, the plurality of doors including a first door and asecond door, wherein

the first and second doors are arranged such that, when the landing gearis deployed, the second door is obstructed from moving between its openand closed positions while the first door is free to move between itsopen and closed positions. One of the first and second doors may bemounted so that the first and second doors may be moved together as aunit for at least a part of the way between the open and closedpositions. Preferably, the first and second doors are moveable togethersubstantially without any relative movement between the first and seconddoors. The first and second doors are advantageously mounted forrotation about a common hinge axis. Other features described above withreference to the present invention may of course be incorporated intothis aspect of the invention. For example, the first and second doorsmay each be mounted for movement by means of a hinge having a pluralityof connection points to a hinge axis, at least one of the connectionpoints of one of the first and second doors being disposed between twoof the connection points of the other of the first and second doors.

DESCRIPTION OF THE FIGURES

By way of example certain embodiments of the invention will now bedescribed with reference to the accompanying drawings, of which:

FIG. 1 is a perspective view from above of an aircraft landing gear doorassembly with all the doors shown closed;

FIG. 2 is a perspective view similar to FIG. 1 but with the landing geardeployed and all the doors open;

FIG. 3 is a perspective view similar to FIG. 2 with the landing geardeployed, but with some of the doors closed;

FIG. 4 is a plan view of a modified form of the landing gear doorassembly shown in FIGS. 1 to 3 with all the doors shown closed;

FIG. 5 is a perspective view of the modified form of landing gear shownin FIG. 4 with some of the doors closed;

FIG. 6 is a perspective view of the assembly shown in FIG. 1 with partof the aircraft skin cut-away and showing mechanisms for opening andclosing the doors; and

FIG. 7 is a partial sectional side view of the door assembly of FIG. 6showing one of the doors in its open position.

DETAILED DESCRIPTION OF THE INVENTION

It should be appreciated that the drawings are schematic and intended toaid understanding of the principles underlying the invention, ratherthan to provide full details of a particular design. In particular, forthe following description it should be assumed that FIGS. 1 to 3 and 6and 7 all relate to the same embodiment, despite the minor differencesin the corresponding drawings.

Referring first to FIG. 1, there is shown an aircraft landing gear doorassembly including a first door 1, a second door 2, a third door 3 and afourth door 4. The doors 1 to 4 are shown in their closed positions inFIG. 1 in which they are closed across an aperture 5 in an aircraft skin6.

The door 1 is rotatably mounted on arms 7 for fixed-axis rotation, theends of the axis 7 opposite the ends that are connected to the doorsbeing connected at connections 8 to mountings (not shown) fixed to theaircraft structure. The door 2 is similarly rotatably mounted on arms 9for fixed-axis rotation about connections 10. Thus the doors 1 and 2 areable to rotate downwardly from the closed positions shown in FIG. 1through an angle of about 90 degrees to the open positions shown in FIG.2.

The door 2 is connected to arms 11 which pass over the exterior of thedoor 1 and through openings in the aircraft skin 6. The ends of the arms11 opposite to those connected to the door 2 are rotatably connected atconnections 12 to mountings (not shown) fixed to the aircraft structure.As can be seen in FIG. 1, the door 2 is mounted for rotation about afixed axis substantially coincident with the axis of rotation of thedoor 1. Similarly the door 4 is connected to arms 13 which pass over theexterior of the door 2 and through openings in the aircraft skin 6. Theends of the arms 13 are rotatably connected at connections 14 tomountings (not shown) fixed to the aircraft structure. As can be seen inFIG. 1, the door 4 is mounted for rotation about a fixed axissubstantially coincident with the axis of rotation of the door 1. Thusthe doors 3 and 4 are able to rotate downwardly from the closedpositions shown in FIG. 1 through an angle of about 90 degrees to theopen position shown in FIGS. 2 and 3.

Hydraulic actuators are provided for controlling movement of the doors,for controlling the locking of the doors in their closed positions andalso for locking the second and fourth doors in their open positions.The hydraulic actuators and associated linkage mechanisms for open andclosing the doors is shown in FIGS. 6 and 7. Those parts are generallynot shown in FIGS. 1 to 3, although locks 15 for locking the doors intheir closed positions and locks 17 for locking the doors 2 and 4 intheir open positions are shown schematically in FIGS. 1 to 3 of thedrawings, but not in FIGS. 6 and 7. Also, it may be noted that theparticular mounting arrangement shown for each of the doors isdifferent; it should be understood that any appropriate mountingarrangement that allows the doors to rotate as required may be adoptedhaving regard to other features of the assembly.

The operation of the doors will now be described with reference to FIGS.1 to 3, 6 and 7.

In the middle of a flight, the doors 1 to 4 will usually be in theirclosed positions as shown in FIG. 1, with the landing gear stowed in thelanding gear bay within the aircraft fuselage or wing, above the closeddoors.

As the aircraft approaches a runway the landing gear needs to bedeployed. To that end, all of the doors 1 to 4 are opened by rotatingthem through about 90 degrees to the position shown in FIG. 2, the firstand second doors being moved together as a unit and the third and fourthdoors being moved together as a unit. It is then possible to deploy thelanding gear, with the whole of the aperture 5 open to allow the landinggear to pass through it. In FIGS. 2 and 3 wheels 16 of the landing gearare shown. When the landing gear is fully deployed the doors 2 and 4 lieadjacent to respective wheels 16.

Once the landing gear has been deployed the first door 1 and the thirddoor 3 are closed. The landing gear and the doors 1 and 3 are arrangedsuch that once the landing gear is fully deployed the doors 1 and 3 canbe locked. This arrangement of the doors is shown in FIG. 3. With onlythe doors 2 and 4 remaining open the aerodynamic effect of the landinggear doors on the aircraft is significantly reduced and the noisegenerated by the doors is also reduced.

The doors 1 and 3 remain closed and the doors 2 and 4 remain open whilethe aircraft lands and, in due course, takes off again. After take offand while the landing gear is still deployed, the doors 1 and 3 areopened again returning the doors to the positions shown in FIG. 2. Thelanding gear is then retracted through the whole of the aperture 5 and,then, all of the doors 1 to 4 are closed.

Breakable couplings are provided between the doors to facilitatemovement of the first and second doors together as a unit and movementof the third and fourth doors together as a unit. FIGS. 6 and 7 showschematically the breakable coupling mechanism and actuators in furtherdetail. In the assembly shown in FIGS. 6 and 7, there is a couplingbetween the first door 1 and the second door 2 with an actuator 22connected only to the first door 1, and similarly there is a couplingbetween the third door 3 and the fourth door 4. The doors are coupledtogether when they are all moved to their open positions of FIG. 2, theyare then decoupled and the doors 1 and 3 then closed. Thereafter, thedoors 1 and 3 are opened, the doors recoupled, and all the doors closed.

As shown in FIG. 6, the actuator 22 acts on the hinge of the first door1. Rotatably mounted to the mid-point of the hinge of the second door 2is a latching arm 21. One end of the arm 21 is provided with a recess 27shaped to accommodate a peg 20, which is fixedly attached to theaircraft structure 6 surrounding the doors 1, 2. The other end of thearm 21 is connected, via a first connecting rod 25, to one arm of arotable crank 28, the other arm of which being connected to a secondconnecting rod 26, which is connected to a locking pin 23. The crank 28is connected to a remotely operable hydraulic actuator 24, that viacrank 28 is able to cause translational movement to rods 25, 26 alongtheir axes and therefore rotational movement of latching arm 21 andtranslational movement of locking pin 23. The actuator 24, arm 27, rods25, 26, crank 28 and pin 23 are all mounted on the second door 2 (or onthe hinge associated with the second door) and therefore rotate with thesecond door 2.

In FIG. 6 the second door 2 is shown coupled by means of locking pin 23being inserted into a pin housing 29 mounted on the first door 1. Whenthe actuator 22 is operated, both the doors 1, 2 move to the openposition locked together by the locking pin 23. At the doors-openposition, the actuator 24 may be operated, pulling back the locking pin23 and, through connecting rods 25 and 26 and crank 28, pivoting thelatching arm 21, the end 27 of which engages with the peg 20 (see FIG.7, which shows the second door 2 in its open position). The second door2 is now locked in the open position and the first door 1 is free to bemoved back to the closed position by actuator 22. Furthermore, thesecond door 2 may be closed thereafter by moving the first door intoalignment with the second door 2, moving the crank 28 (by means of theactuator 24) simultaneously to unlock the second door from its openposition (by disconnecting the arm 21 and the peg 20) and to couple thesecond door to the first door (by means of inserting the locking pin 23into the housing 29).

The breakable couplings and actuators shown schematically in FIGS. 6 and7 are associated with the first and second doors 1, 2. It will beunderstood that similar means are provided in respect of the third andfourth doors 3, 4.

FIGS. 4 and 5 illustrate schematically a modified design in which thesecond door 2 of the assembly shown in FIGS. 1 to 3 is replaced by asecond door 2 a and the fourth door 4 of the assembly shown in FIGS. 1to 3 is omitted. The door 2 a, when closed, is disposed between thedoors 1 and 3 and the arrangement is approximately symmetrical about avertical plane P (FIG. 4). The modified assembly of FIGS. 4 and 5operates in substantially the same way as the assembly of FIGS. 1 to 3with the door 2 a moving in the same manner as the door 2 of theassembly described with reference to FIGS. 1 to 3. In FIG. 5 the wheelsof the landing gear are not shown but it will be understood that thedoor 2 a is disposed adjacent to the wheels, but that there is nocorresponding door on the other side of the wheels.

The assembly of FIGS. 4 and 5 has the advantage that there is one lessdoor to move and that only one door remains open after deployment of thelanding gear, but has the disadvantage that the one door that doesremain open has to be bigger and project further down in its openposition, than if a pair of doors each of half the size were employed.

In the embodiment illustrated in FIGS. 1 to 3 and 6 and 7 describedabove, the doors are coupled so that a pair of doors may be moved bymeans of a single actuator. An alternative arrangement is to provideactuators so that each door is independently moved by its own hydraulicactuator.

1. An aircraft landing gear door assembly comprising a plurality ofdoors moveable between open positions, in which a landing gear can bedeployed through an aperture, and closed positions, in which the doorsare closed across the aperture, the plurality of doors comprising afirst door and a second door, wherein during at least part of saidmovement of the plurality of doors, the movement of at least the firstdoor of the plurality of doors is independent of the movement of thelanding gear, the first and second doors are so arranged that they are,when installed on an aircraft, configurable in such a way that movementof one of the first and second doors for at least a part of the waybetween the open and closed positions causes movement of the other ofthe first and second doors, and the first and second doors are arrangedsuch that, when the landing gear is deployed, the second door isobstructed from moving between its open and closed positions while thefirst door is free to move between its open and closed positions.
 2. Anassembly according to claim 1, wherein the first and second doors aremounted such that they may be moved together between the open and closedpositions substantially without any relative movement between the firstand second doors.
 3. An assembly according to claim 1, wherein one ofthe first and second doors is mounted for rotational movement about afixed axis.
 4. An assembly according to claim 1, wherein the first andsecond doors are mounted for rotation about a fixed axis, the fixed axesof rotation of the first and second doors being substantiallycoincident.
 5. An assembly according to claim 1, wherein the first andsecond doom are each mounted for movement by means of a connectionhaving a plurality of connection points, at least one of the connectionpoints of one of the first and second doors being disposed between twoof the connection points of the other of the first and second doors. 6.An assembly according to claim 1, in which the first and second doorsare arranged so that they may be coupled together to move as a singleunit between their open and closed positions, and be decoupled to enablethe first door also to move independently of the second door between itsopen and closed positions.
 7. An assembly according to claim 1, inwhich, when the doors are in their open positions, the second door isdisposed below the first door.
 8. An assembly according to claim 7, inwhich the second door is mounted on at least one arm, said at least onearm having one end and an other end, the at least one arm connected atone end to the second door and is moveably mounted at its other end toallow the movement of the second door between its open and closedpositions.
 9. An assembly according to claim 1, in which the pluralityof doors further comprises a third door moveable between closed and openpositions, the first and third doors defining a pair of doors onopposite sides of the aperture through which the landing gear isdeployed.
 10. An assembly according to claim 9, in which the third dooris mounted for rotational movement about a fixed axis.
 11. An assemblyaccording to claim 9 in which the third door is arranged such that, whenthe landing gear is deployed, it is free to move between its open andclosed positions.
 12. An assembly according to claim 9, in which theplurality of doors includes a fourth door mounted for movement betweenclosed and open positions, the third and fourth doors being arrangedsuch that, when the landing gear is deployed, the fourth door isobstructed from moving between its open and closed positions while thethird door is free to move between its open and closed positions.
 13. Anassembly according to claim 12, in which the fourth door is mounted forrotational movement about a fixed axis.
 14. An assembly according toclaim 13, in which the fixed axes of rotation of the third and fourthdoors are substantially coincident.
 15. An assembly according to claim12, in which the third and fourth doors are arranged so that they may becoupled together to move as a single unit between their open and closedpositions, and be decoupled to enable the third door also to moveindependently of the fourth door between its open and closed positions.16. An assembly according to claim 12, in which, when the third andfourth doors are in their open positions, the fourth door is disposedbelow the third door.
 17. An assembly according to claim 16, in whichthe fourth door is mounted on at least one arm which is connected at oneend to the second door and is moveably mounted at its other end to allowthe movement of the fourth door between its open and closed positions.18. An aircraft landing gear door assembly comprising a plurality ofdoors moveable between open positions, in which a landing gear can bedeployed through an aperture, and closed positions, in which the doorsare closed across the aperture, the plurality of doors comprising afirst door, a second door, a third door and a fourth door, wherein thefirst and second doors are so arranged that they are, when installed onan aircraft, configurable in such a way that movement of one of thefirst and second doors for at least a part of the way between the openand closed positions causes movement of the other of the first andsecond doors, the first and second doors are arranged such that, whenthe landing gear is deployed, the second door is obstructed from movingbetween its open and closed positions while the first door is free tomove between its open and closed positions, the third and fourth doorsare so arranged that they are, when installed on an aircraft,configurable in such a way that movement of one of the third and fourthdoors for at least a part of the way between the open and closedpositions causes movement of the other of the third and fourth doors,the third and fourth doors are arranged such that, when the landing gearis deployed, the fourth door is obstructed from moving between its openand closed positions while the third door is free to move between itsopen and closed positions, the first and third doors defining a firstpair of doors on opposite sides of the aperture through which thelanding gear is deployed, the second and fourth doors defining a secondpair of doors on opposite sides of the aperture through which thelanding gear is deployed.
 19. An assembly according to claim 18, inwhich each of the first, second, third and fourth doors are mounted forrotational movement about a fixed axis, the fixed axes of rotation ofthe first and second doors being substantially coincident and the fixedaxes of rotation of the third and fourth doors also being substantiallycoincident.
 20. An aircraft including a landing gear door assemblyaccording to claim 1 and the landing gear with which the landing geardoor assembly is associated.